Developing an African VLBI Network Michael Gaylard Hartebeesthoek Radio Astronomy Observatory (HartRAO) P. O. Box 443, Krugersdorp 1740, South Africa www.hartrao.ac.za [email protected] The SKA is coming... Africa Australia Phase 1: 0.45 – 3 GHz Phase 1: 0.45 – 3 GHz Over 100 km Dishes < 100 km Phase 2: 0.45 – 10 GHz Over 3000 km + 64 MeerKAT dishes + 36 ASKAP dishes 0.4 – 1.4 GHz 70 – 450 MHz Dense Aperture Array, Phase 2 Sparse Aperture Array, Phase 2 SKA-SA proposed siting – Southern Africa Phase 1 Phase 2 SKA-SA proposed siting - Africa Preparing for SKA Long Baselines: Current VLBI-capable Radio Telescopes in Africa VLBI - Very Long Baseline Interferometry 26m and 15m Radio Telescopes, HartRAO, South Africa Preparing African Partner Countries for SKA Long Baseline Stations - 1 South Africa's Department of Science and Technology and SKA-SA have been working with partner countries: Obtaining political buy-in Obtaining infrastructure information Identifying potential SKA outstation sites Funding training in SA of students from partner countries as astronomers, engineers, technologists Preparing African Partner Countries for SKA Long Baseline Stations - 2 Capacity development: Organisational structures to support outstation operation – visa facilitation, import/export of equipment Availability of wideband internet connection at sites costed at academic rates Availability of technical / engineering capability to support operations Availability of electrical power to meet reliability requirement Establishing benefits for the partner countries Preparing African Partner Countries for SKA Long Baseline Stations - 3 Benefits for partners – what is in it for them? Participate in SKA science? Participate in SKA development? Development of internal capacity / capability? Preparing African Partner Countries for SKA Long Baseline Stations - 4 The best way to learn / prepare is by doing: Could we establish a VLBI-capable radio telescope in each country ahead of the SKA? What science could they do? Could they work with existing VLBI networks? Could a stand-alone VLBI capability be developed? DST proposal for the above was funded by SA's African Renaissance Fund and DST for ~$14m. Preparing African Partner Countries for SKA Long Baseline Stations - 5 SKA-SA Africa bid participating countries European VLBI Network + HartRAO UV-plot for source at Dec +20o European VLBI Network The large gap between Europe and South Africa leads to missing information and poor image quality Australia Telescope Long Baseline Array + HartRAO The long gap between the telescopes caused by the Indian Ocean means the “synthetic telescope” provided by Earth rotation has substantial missing information, reducing image quality African Undersea Cables An enabling technology for the SKA in future, And for long baseline radio astronomy now The new technology is also making old, large satellite antennas obsolete Hart - EVN 32 Mbps Hart – EVN 10 Gbps Africa – Large Satellite Antennas Existing and Possible New Antennas in SKA-SA partner countries SKA-SA Partner Satellite Stations Kenya Ghana Longonot Kutunse Madagascar Tsirinana Zambia South Africa Mwembeshi Hartebeesthoek Telkom Networks that could benefit from more radio telescopes in Africa European VLBI Network (EVN) Global Array (EVN + US VLBA) Australia Telescope Long Baseline Array (AT-LBA) Astrometry and Geodesy Network (IVS) MeerKAT SKA An African VLBI Network: needs 4+ antennas for an independent imaging capability EVN with HartRAO + Ghana Filling the gap with Ghana or Kenya gives much superior imaging EVN with HartRAO + Kenya Longonot satellite station in Kenya – 1x30m out of use, 1x32m still in limited use 30m is similar to Goonhilly 3 Australia Telescope LBA + HartRAO + Mauritius Having telescopes on the Indian Ocean islands would grealt reduce the gap and improve image quality. There is no large satellite antenna available on Mauritius – a new large antenna would have to be built Australia Telescope LBA + HartRAO + Madagascar Madagascar has a large satellite antenna that could be converted for radio astronomy as its communications role diminishes or is no longer commercially viable. This would expected to be much cheaper than a newbuild of the same size. Benefits of antenna conversion for the host country Re-use of an expensive installation that is now or is becoming redundant, at relatively low cost In country training in practical radio astronomy: Single-dish research, student projects and practicals Long baseline astronomy for high angular resolution imaging Create a pool of astronomers able to use current and future radio telescope arrays Create a pool of engineers and technicians able to support SKA outstations Stimulate fibre optic network development with spinoffs for the country Opportunities for training, research and development in engineering and technology: advanced microwave feeds, low-noise amplifiers and receiver systems analogue and digital electronics digital signal processing control and monitoring systems software engineering wide bandwidth communications networks Stimulate interest in science, engineering and technology through outreach programme Promote the establishment / development of a national Space / Astronomy Agency Establish other science instruments for multi-disciplinary science, eg: GPS base-station, gravimeter, seismometer, magnetometer Science Objectives – VLBI Astronomy Imaging with high angular resolution of bright radio sources of small angular size: Quasars (AGNs) – understanding Jets, use as calibrators, references for parallaxes Gamma-ray flare & burster followup (HESS II in Namibia, FERMI-LAT, CTA) Masers – interstellar (e.g. methanol) – investigate variability / periodicity; measure maser spot movements; measure annual parallax to determine the distances to star-forming regions in the Milky Way and map the spiral arms Supernovae – behaviour of remnants of core-collapse supernovae, determine distances Pulsars – proper motions and distance determination through annual parallax, interstellar magnetic fields interstellar scattering, emission region size Transient radio source behaviour Interacting binary star behaviour e.g. Circinus X-1 Rapid response to new events - E-VLBI and TOO VLBI through internet Celestial and Terrestrial Reference Frames development Compare with SKA long baseline science case: "Memo 135 Very High Angular Resolution Science with the SKA", L. Godfrey, H. Bignall, S. Tingay, May 2011, and summarised in "Science at Very High Angular Resolution with the Square Kilometre Array", E. H. Godfrey, et al., Publ. Astron. Soc. Australia, 2012, 29, 42–53. Science Objectives – Single-Dish Astronomy West African and Central African stations: Near equator so see more of the sky than any other similar radio telescope Can see the entire Milky Way Galaxy Single dish research / training opportunity examples: Spectroscopy with narrowband multi-channel receiver Monitor masers in star-forming regions eg for periodic variations (e.g. methanol at 6668MHz, 12178MHz) Survey formaldehyde absorption in Milky Way dark clouds (4829 MHz, 14488MHz) Pulsar observing with wideband multi-channel timer Monitor pulsars for glitches, long term behaviour, proper motion Search / monitor for intermittent pulsars and transients (RRATs) Radio continuum flux measurement with wideband multi-channel radiometer Monitoring of Gamma-ray flare sources FPGA-based board with suitable software can do all three of these tasks Process for Conversions Assist in establishing organisation in host country to operate the facility Establish training of engineers, technicians, astronomers Evaluate structural, mechanical and electronic needs for converting the antenna for radio astronomy Carry out mechanical & control system upgrades as needed Test with simple 5 GHz receiver on existing 4 - 6 GHz feed, permitting basic single-dish & VLBI testing Build 5 + 6.7 GHz receivers for existing feed to develop an operational VLBI capability Commission for operational VLBI at 5 + 6.7 GHz, operation by host country Evaluate options for operation at other frequencies, e.g 1.4 – 1.7 GHz eg as Ceduna Implement multi-frequency option selected Upgrade to cryogenic receivers Antenna conversion examples Top row are operational as radio telescopes: Australia Ceduna Japan Yamaguchi Japan Ibaraki USA NASA DSS28 New Zealand England Goonhilly – Ireland Elfordstown – Peru Sicaya – First Warkworth - handed handed over 2011/05 funded 2012 light 2011/03 over 2010/11 SA Development team Development team has been established at SKA- SA offices in Cape Town and at HartRAO: Project Manager (engineer) Mechanical engineer and technicians Electronic engineer and technicians Software engineer and technicians RF engineer and technicians being recruited Systems test and verification engineer + part time commitments from HartRAO staff First test receiver for Ghana antenna, in development at HartRAO Expanding the African VLBI Network Importance of Madagascar in a network of converted large satellite antennas in filling gaps in coverage Adding new-build telescopes would improve imaging capability UV coverage with all large satellite UV coverage with all large satellite antennas converted, antennas converted and four new-builds, for source at Dec -20 for source at Dec -20 Potential New-Build Telescopes SKA-SA Partner Countries: Botswana, Mauritius, Mozambique, Namibia Functions: Training Science Compatibility with existing VLBI Networks Enhance stand-alone AVN VLBI capability